The invention relates to a tube to be connected to a pipe having a projecting portion at an insertion end portion, more particularly, an improvement of a connecting structure of the tube to be connected to the pipe.
Heretofore, a connector for connecting a pipe made of a, relatively hard material, such as steel, and a tube made of a relatively soft material, such as synthetic resin, has been, disclosed in, for example, Japanese Patent Publication (KOKAI) No. 5-196184.
The conventional connector, as shown in FIGS. 5(a) and 5(b), connects a tube T having a uniform outer diameter, to a pipe P having an insertion end portion P1 with a uniform outer diameter and a flange portion F on a circumference of the insertion end portion P1. The connector includes a connector main portion C and a retainer R.
The connector C is formed of a mounting portion C1, a base portion C2 and an attaching portion C3, which are integrally molded. The mounting portion C1 has a cylindrical shape with a small diameter and a plurality of annular projections K of a hook shape on its outer circumferential surface. The base portion C2 has a cylindrical shape of a sufficiently larger diameter than the insertion end portion P1 of the pipe P, and houses therein a pair of O-rings 01, 02, and a spacer S. The attaching portion C3 has a cylindrical shape of a diameter larger than that of the base portion C2, and is provided with a pair of windows W at mutually facing portions. The connector main portion C is attached to the tube T by inserting the mounting portion C1 into an opening end portion of the tube T.
The retainer R has a pair of openable elastic tongues A, and is attached to the attaching portion C3 such that the tongues A are fitted in the respective windows W. The elastic tongues A are gradually inclined inwardly toward the base portion C2 of the connector main portion C to thereby form a space smaller than an outer diameter of the flange portion F between the forward ends thereof.
In the conventional technique, when the pipe P is inserted into the connector main portion C, the elastic tongues A are pressed in a direction radially outwardly by the flange portion F, so that the elastic tongues A are suitably widened to thereby allow the flange portion F to pass therethrough. Thereafter, when the flange portion F has passed through the elastic tongues A, the respective tongues A return to the normal states by their respective restoring forces, and the respective forward ends of the elastic tongues A are pressed against the circumferential surface of the pipe P on the base end side of the flange portion F.
As a result, the pipe P is prevented from being disengaged from the connector through the flange portion F to thereby hold a connecting state between the pipe P and the tube T.
In case the conventional connector is used, as described above, since the pipe P and the tube T can be mutually connected by the insertion operation of the pipe P, the connecting operation can be easily carried out.
Also, in the insertion operation, the insertion force is suddenly changed after the forward ends of the elastic tongues A pass the flange portion F to thereby give an operator a moderate feeling, so that the operator can acknowledge the connecting state between the pipe P and the tube T through the moderate feeling.
However, in the above-described connector, it is necessary that the mounting portion C1 of the connector main portion C is inserted into an opening end portion of the tube T. The insertion operation of the mounting portion C1 requires a great force and is extremely troublesome since the mounting portion C1 is pushed while gradually widening an inner diameter of the tube T.
Moreover, in case the above-described connector is used, it is necessary that not only the connector main portion C and the retainer but also the O-rings 01, 02 and 03 are interposed over the tube T and the pipe P. As a result, the number of parts for connecting the pipe P and the tube T becomes extremely large, which results in a high cost.
In view of the above defects, the present invention has been made, and an object of the invention is to provide a tube which can be connected to a pipe with an easy operation.
Another object of the present invention is to provide a tube as stated above, wherein a production cost can be greatly reduced.
Further objects and advantages of the invention will be apparent from the following description of the invention.